1. Field of the Invention
Example embodiments of the present invention relate to semiconductor devices and methods of fabricating the same, for example, to semiconductor devices having nitrogen-incorporated active regions and methods of fabricating the same.
2. Description of the Related Art
In related art semiconductor devices, a silicon oxide layer such as a thermal oxide layer may be used as a film-forming material of a gate dielectric layer. When the silicon oxide layer is formed to a thickness of 2 nm or less leakage current may increase more rapidly. In order to suppress the leakage current from increasing, high-k dielectric layers having a dielectric constant higher than that of the silicon oxide layer may be used as the film-forming material of the gate dielectric layer instead of the silicone oxide layer. The high-k dielectric layer may have a smaller equivalent thickness as compared to the silicon oxide layer. For example, the high-k dielectric layer may be used as the film-forming material of the gate dielectric layer to produce semiconductor devices having a smaller equivalent thickness while maintaining a thickness capable of suppressing leakage current.
Related art semiconductor devices may include transistors requiring different electrical characteristics from each other within a semiconductor substrate. For example, a related art complementary metal oxide semiconductor (CMOS) device may include an N-channel metal oxide semiconductor (NMOS) transistor and a P-channel metal oxide semiconductor (PMOS) transistor within the same substrate. An access transistor may be disposed in a cell region of the semiconductor device, and a drive transistor may be disposed in a peripheral circuit region of the semiconductor device. Different gate dielectric layers for each of the transistors may be formed sequentially in the related art. However, this may require a more complicated fabrication process and/or increase fabrication time.
In another related art method, a semiconductor device may have a plurality of transistors having gate dielectric layers with different characteristics. The gate dielectric layers of the transistors may have a high-k dielectric layer and interface layers formed by a reaction between the high-k dielectric layer and the silicon substrate. A nitrogen ion incorporated layer may be formed on the surface of the silicon substrate prior to the formation of the high-k dielectric layer. Accordingly, the growth of the interface layer may be suppressed. As a result, the interface layer formed on the nitrogen ion incorporated layer may have a thickness smaller than the interface layer formed on the semiconductor substrate without the nitrogen ion incorporated layer. These transistors may exhibit different characteristics.